To drive round a bend, in tracked vehicles the track on the side of the vehicle on the outside of the bend is driven faster than the track on the side of the vehicle on the inside of the bend. During this the mechanical power on the track on the outside of the bend is much higher than on the track on the inside of the bend. This results in the production of so-termed reactive power, which circulates between the sides of the vehicle on the inside and outside of the bend. In conventionally driven tracked vehicles with a combustion engine and a steering transmission, this reactive power circulates from the track on the outside of the bend, via the ground, to the track on the inside of the bend and then, by way of cross-shafts, namely a neutral shaft and a central shaft, back to the track on the outside of the bend.
Various electric motor drive mechanisms for tracked vehicles are already known. The electrical energy for the electric motors is for example supplied by a generator driven by an internal combustion engine. In a simply designed version of an electric motor drive mechanism for tracked vehicles, each of the two tracks is driven directly by a separate electric motor. In this case each electric motor provides both the drive power and the steering power for the associated side or track of the vehicle. However, this has the disadvantage that when rounding a bend the reactive power cannot be transmitted via a mechanical connection such as a cross-shaft and must therefore be supplied by the electric motors. Because of that the electric motors of such a drive mechanism have to be greatly oversized, and this leads to higher costs and increased vehicle weight.
From DE 60206481 T2 a drive configuration for tracked vehicles is known, which avoids the disadvantage of oversize electric drive motors. This is achieved in that a conventional drive mechanism is modified with a neutral shaft and a central shaft in such manner that an electric drive motor is arranged on the central shaft and drives it, and an electric steering motor is arranged on the neutral shaft and drives it. Thus, when driving round a bend the reactive power described can be transmitted from the track on the outside of the bend to the track on the inside of the bend by means of mechanical elements consisting essentially of the neutral shaft and the central shaft.
Besides, still other electric motor drive mechanisms for tracked vehicles are known, in which, while rounding a bend the reactive power is transmitted from one drive side to the other drive side by mechanical drive elements. For example, WO 2009/013454 A1 describes a drive mechanism for tracked vehicles with a respective electric drive motor and a respective electric steering motor for each drive side or track. In this case the two drive motors each drive a respective driveshaft which drive their associated tracks respectively on each side of the tracked vehicle. To drive round a bend steering power or steering rotational movement is transmitted by the steering motors via a centrally positioned differential transmission to the two driveshafts. Thus, here too the reactive power while rounding a bend can be supported, namely by means of the differential transmission.
However, all the electrical drive mechanisms described above demand relatively high electric power and therefore take up a relatively large amount of fitting space in the tracked vehicle and thus is no longer available as access space or payload space. In addition, the necessary electric drive power increases the overall weight and the operating costs of the tracked vehicle.